Laura Johnson

Laura Johnson
Position: 
Research Scientist
Education/Degrees: 
B.S., Virginia Tech
Education/Degrees: 
Ph.D., University of Notre Dame
Unit (Dept., Office, Center, etc.): 
Contact Information
Phone Number: 
(419) 448-2056
Office Location: 
National Center for Water Quality Research
Gillmor 308

Background

Laura recently joined the National Center for Water Quality Research (NCWQR) in January 2013. Prior to this, she was a postdoctoral research associate in Dr. Todd Royer’s Laboratory at Indiana University in Bloomington. Laura received her Ph.D. from the University of Notre Dame in 2008 where she worked with Dr. Jennifer Tank on the effect of human land use on stream nutrient processing. Laura started conducting research as an undergraduate at Virginia Tech in the Stream Team- a collaborative laboratory of Drs. Jack Webster, Fred Benfield, and Maury Valett. She graduated in 2002 with a B.S. in Biology.

Research Interests

Aquatic ecosystem ecology and biogeochemistry, i.e., the transport and storage of materials (nutrients, gases, sediment, organic matter) in aquatic environments

Current Research

At the NCWQR, Laura is primarily focused on watershed export and riverine dynamics of phosphorus, nitrogen, and sediment. She is working on projects investigating the influence of soil phosphorus stratification on dissolved phosphorus runoff and is involved in the Tributary Loading Program.

Past Research

Before arriving at the NCWQR, Laura was involved in a variety of projects from her postdoc and graduate career. These include (but are not limited to):

• The role of artificial subsurface drainage on greenhouse gas emissions (CO2, CH4, N2O) from an agricultural watershed

• Linkages among dissolved organic carbon availability, microbial diversity, and nitrogen removal via denitrification, the microbially-mediated reduction of nitrate to N2 and N2O

• Interactions between nitrogen and phosphorus in a forested stream- the influence of changing nutrient concentrations on retention and saturation kinetics

• Nutrient limitation of benthic algae and phytoplankton along a salinity gradient in the Altamaha River estuary on the coast of Georgia

• The effect of human land use on dissolved organic carbon and nitrogen uptake in streams

• The influence of human land use on biofilm nutrient limitation in 72 streams across North America

Laura was also involved in two large collaborative projects during graduate school including:

• The Lotic Intersite Nitrogen eXperiment II (LINX II)- a project that examined the influence of human land use on the fate of nitrate in streams using 24-h 15N-nitrate tracer additions.

• The Nature Conservancy Two Stage Ditch project- a study investigating the effect of expanding the area riparian benches on nitrate removal in an agricultural stream. These riparian benches are within the incised channel act and as act as mini-floodplains when inundated during high flows.

Professional Experience

2013-present: Research Scientist, National Center for Water Quality Research, Heidelberg University

2008-2012:  Postdoctoral Research Associate- with Dr. Todd V. Royer at the School of Public and Environmental Affairs, Indiana University, Bloomington, IN

2006-2007:  Research Assistant- The Nature Conservancy Two Stage Ditch Project, Department of Biological Sciences, University of Notre Dame

2002-2006:  Research Assistant- Lotic Intersite Nitrogen eXperiment II, Department of Biological Sciences, University of Notre Dame

2002-2008:  Teaching Assistant, Department of Biological Science, University of Notre Dame

2000-2002:  Research Experience for Undergraduates (REU) internship and laboratory assistant, Stream Ecology Laboratory, Virginia Tech

Publications

Baxter, A.M., L.T. Johnson, T.V. Royer, and L.G. Leff. In Press. Spatial differences in denitrification and bacterial community structure of streams: relationships with environmental conditions. Aquatic Sciences. DOI: 10.1007/s00027-012-0272-5.

Johnson, L.T., T.V. Royer, J.M. Edgerton, and L.G. Leff. 2012. Manipulation of the dissolved organic carbon pool in an agricultural stream: responses in microbial community structure, denitrification, and assimilatory nitrogen uptake. Ecosystems 15: 1027-1038.

Baxter, A.M., L.T. Johnson, J. Edgerton, T.V. Royer, and L.G. Leff. 2012. Structure and function of denitrifying bacterial assemblages in low order Indiana streams. Freshwater Science (formerly Journal of the North American Benthological Society) 31: 304-317.

Roley S.S., J.L.Tank, M.L. Stephen, L.T. Johnson, and J.J. Beaulieu. 2012. Floodplain restoration enhances denitrification and reach-scale nitrogen removal in an agricultural stream. Ecological Applications 22: 281-297.

Beaulieu, J.J., J.L. Tank, S.K. Hamilton, W.M. Wollheim, R.O. Hall, P.J. Mulholland, B.J. Peterson, L.R. Ashkenas, L.W. Cooper, C.N. Dahm, W.K. Dodds, N.B. Grimm, S.L. Johnson, W.H. McDowell, G.C. Poole, J.L. Meyer, H.M. Valett, J.R. Webster, C.P. Arango, M.J. Bernot, A.J. Burgin, C.L. Crenshaw, A.M. Helton, L.T. Johnson, J.M. O’Brien, J.D. Potter, R.W. Sheibley, D. J. Sobota, and S.M. Thomas. 2010. Nitrous oxide emission from denitrification in stream and river networks. Proceedings of the National Academy of Sciences 108: 214-219.

Bernot, M.J., D.J. Sobota, R.O. Hall, P.J. Mulholland, W.K. Dodds, J.R. Webster, J.L. Tank, L.R. Ashkenas, L.W. Cooper, C.N. Dahm, N.B. Grimm, S.V. Gregory, S.K. Hamilton, S.L. Johnson, W.H. McDowell, J.L. Meyer, B.J. Peterson, G.C. Poole, H.M. Valett, C.P. Arango, J.J. Beaulieu, A.J. Burgin, C.L. Crenshaw, A.M. Helton, L.T. Johnson, J. Merriam, B.R. Niederlehner, J.M. O’Brien, J.D. Potter, R.W. Sheibley, S.M. Thomas, and K.Wilson. 2010. Inter-regional comparison of land-use effects on stream metabolism. Freshwater Biology 55: 1874-1890.

Johnson, L.T., C.P. Arango, and J.L.Tank. 2009. The effect of land use on dissolved organic carbon and nitrogen uptake in streams. Freshwater Biology 54: 2335-2350.

Johnson, L.T., and J.L. Tank. 2009. Diurnal variations in dissolved organic matter and ammonium uptake in six open-canopy streams. Journal of the North American Benthological Society 28(3): 694-708.

Johnson, L.T.
, J.L. Tank, and W.K. Dodds. 2009. The influence of land use on stream biofilm nutrient limitation across eight North American ecoregions. Canadian Journal of Fisheries and Aquatic Sciences 66: 1081-1094.

Mulholland, P.J., R.O. Hall, D. J. Sobota, W.K. Dodds, S.E. Findlay, N.B. Grimm, S.K. Hamilton, W.H. McDowell, J.M. O’Brien, J.L. Tank, L.R. Ashkenas, L.W. Cooper, C.N. Dahm, S.V. Gregory, S.L. Johnson, J.L. Meyer, B.J. Peterson, G.C. Poole, H.M. Valett, J.R. Webster, C.P. Arango, J.J. Beaulieu, M.J. Bernot, A.J. Burgin, C.L. Crenshaw, A.M. Helton, L.T. Johnson, B.R. Niederlehner, J.D. Potter, R.W. Sheibley, and S.M. Thomas. 2009. Nitrate removal in stream ecosystems measured by 15N addition experiments: Denitrification. Limnology and Oceanography 54(3): 666-680.

Hall, R.O., J.L. Tank, D. J. Sobota, P.J. Mulholland, J.M. O’Brien, W.K. Dodds, J.R. Webster, H.M. Valett, G.C. Poole, B.J. Peterson, J.L. Meyer, W.H. McDowell, S.L. Johnson, S.K. Hamilton, N.B. Grimm, S.V. Gregory, C.N. Dahm, L.W. Cooper, L.R. Ashkenas, S.M. Thomas, R.W. Sheibley, J.D. Potter, B.R. Niederlehner, L.T. Johnson, A.M. Helton, C.L. Crenshaw, A.J. Burgin, M.J. Bernot, J.J. Beaulieu, and C.P. Arango. 2009. Nitrate removal in stream ecosystems measured by 15N addition experiments: Total uptake. Limnology and Oceanography 54(3): 653-665.

Arango, C.P., J.L. Tank, L.T. Johnson, and S.K. Hamilton. 2008. Assimilatory uptake rather than dissimilary transformation determines seasonal patterns in nitrogen removal in streams of varying land use. Limnology and Oceanography 53(6): 2558-2572.

Mulholland, P.J., A.M. Helton, G.C. Poole, R.O. Hall, S.K. Hamilton, B.J. Peterson, J.L. Tank, L.R. Ashkenas, L.W. Cooper, C.N. Dahm, W.K. Dodds, S.E. Findlay, S.V. Gregory, N.B. Grimm, S.L. Johnson, W.H. McDowell, J.L. Meyer, H.M. Valett, J.R. Webster, C.P. Arango, J.J. Beaulieu, M.J. Bernot, A.J. Burgin, C.L. Crenshaw, L.T. Johnson, B.R. Niederlehner, J.M. O’Brien, J.D. Potter, R.W. Sheibley, D. J. Sobota, and S.M. Thomas. 2008. Stream denitrification across biomes and its response to anthropogenic nitrate loading. Nature 452: 202-246.

Memberships in Professional Associations

• Society for Freshwater Science
• American Society for Limnology and Oceanography
• Ecological Society of America
• International Association of Great Lake Research
• Sigma Xi, The Scientific Research Society
• National Society of Collegiate Scholars

First-Author Presentations at Scientific Conferences

Johnson, L.T., T.V. Royer, R.P. Phillips, and D. Oviedo-Vargas. The role of artificial subsurface drainage in greenhouse gas emissions from an agricultural watershed. 60th annual Society for Freshwater Science meeting. Louisville, KY, May 2012

Johnson, L.T., T.V. Royer, D. Oviedo-Vargas, and L.G. Leff. Effect of a labile carbon addition on nitrogen cycling in a nitrate-rich stream in Indiana, USA. 59th annual North American Benthological Society Conference. Providence, RI, May 2011.

Johnson, L.T., T.V. Royer, J.M. Edgerton, and L.G. Leff. Effect of a labile DOC addition on nitrogen cycling in an agricultural stream. 58th annual North American Benthological Society Conference joint with the American Society of Limnology and Oceanography summer meeting. Santa Fe, NM, June 2010.

Johnson, L.T., T.V. Royer, L.G. Leff, J.M. Edgerton, A.M. Baxter, M.P. Brennan, and D.Oviedo-Vargas. The influence of dissolved organic matter on denitrifier community composition and denitrification rates in an agricultural headwater stream. 94th annual Ecological Society of America meeting. Albuquerque, NM, August 2009. Poster.

Johnson, L.T., J.L. Tank, P.J. Mulholland, R.O. Hall, S. Findlay, W.H. McDowell, H. M. Valett, S.K. Hamilton, B.J. Peterson, L.R. Ashkenas, L.W. Cooper, C.N. Dahm, W.K. Dodds, S.V. Gregory, N.B. Grimm, S.L. Johnson, J.L. Meyer, G.C. Poole, J.R. Webster, C.P. Arango, J,J. Beaulieu, M.J. Bernot, A.J. Burgin, C.L. Crenshaw, A. M. Helton, B.R. Niederlehner, J.M. O'Brien, J.D. Potter, R.W. Sheibley, D.J. Sobota, and S.M. Thomas. The fate of assimilated 15N-nitrate in 71 headwater streams. 56th annual North American Benthological Society Conference. Salt Lake City, UT, May 2008.

Johnson, L.T., J.L. Tank, R.O. Hall, and P.J. Mulholland. The influence of land use on autochthonous DON production in streams from two contrasting biomes. 55th annual North American Benthological Society Conference. Columbia, SC, June 2007.

Johnson, L.T. and J.L. Tank. The effect of land use on DOC and DON uptake in headwaters stream in the Kalamazoo River basin, Michigan. American Society of Limnology and Oceanography Aquatic Sciences Meeting. Sante Fe, NM, February 2007.

Johnson, L.T. and J.L. Tank. Diel fluctuations of DOC and DON uptake in streams. 54th annual North American Benthological Society Conference. Anchorage, AK, June 2006.

Taylor, L.C. and J.L. Tank. The effect of land use on DOC and DON uptake in headwater streams in the Kalamazoo River basin, Michigan.53rd annual North American Benthological Society Conference. New Orleans, LA, June 2005.

Taylor, L.C., J.L. Tank, W.K. Dodds, and K.C. Wilson. The influence of land use on biofilm nutrient limitation across 8 North American biomes. 52nd annual North American Benthological Society Conference. Vancouver, BC, Canada, June 2004.

Taylor, L.C., J.L. Tank, and G.A. Lamberti. 2003. How the addition of salmon carcasses vs. salmon analog affects nutrient export in an Alaskan stream. 51st annual North American Benthological Society Conference. Athens, GA, May 2003. Poster.